Leonardo da Vinci’s multi-barreled firearm design was commonly called an organ gun.
An organ gun is a firearm with several barrels arranged side by side or in groups, allowing repeated shots without reloading after every discharge. Leonardo designed a version with multiple small gun barrels mounted on a frame. The visual arrangement resembled the pipes of a musical organ, which explains the name used for this class of weapon.
Leonardo’s military notebooks contain several proposals for improving battlefield artillery and hand firearms. A multi-barreled weapon could deliver a concentrated volley and reduce the delay between individual shots, although it would still require loading, powder, and maintenance. The design was not a modern machine gun because it lacked automatic loading and continuous mechanical firing.
The organ gun is sometimes described as a “33-barrelled cannon” in popular accounts, but the exact configuration depends on which drawing or reconstruction is being discussed. The safest historical description is a multi-barreled firearm concept. There is no reliable evidence that Leonardo’s particular design became a standard weapon in Renaissance warfare.